This disclosure relates to methods of servicing a wellbore. More specifically, it relates to methods of treating a wellbore with permeability modifying and/or sealing compositions.
Natural resources (e.g., oil or gas) residing in a subterranean formation may be recovered by driving resources from the formation into a wellbore using, for example, a pressure gradient that exists between the formation and the wellbore, the force of gravity, displacement of the resources from the formation using a pump or the force of another fluid injected into the well or an adjacent well. The production of fluid in the formation may be increased by hydraulically fracturing the formation. That is, a viscous fracturing fluid may be pumped down the wellbore at a rate and a pressure sufficient to form fractures that extend into the formation, providing additional pathways through which the oil or gas can flow to the well. Subsequently, oil or gas residing in the subterranean formation may be recovered by driving the fluid into the well using, for example, a pressure gradient that exists between the formation and the wellbore, the force of gravity, displacement of the fluid using a pump or the force of another fluid injected into the well or an adjacent well.
Unfortunately, water along with oil or gas may eventually be produced by the formation through the fractures therein. In such cases, the formation may be treated with a relative permeability modifier (RPM) that is meant to control water production, shut off water-producing intervals, and/or enhance hydrocarbon production.
Generally, two adjacent wells may be used in an enhanced oil recovery (EOR) operation, where a fluid is swept between the two adjacent wells. In EOR, a sweeping fluid may be injected in one of the wells, allowed to sweep across the formation, and then recovered along with the natural resources (e.g., oil or gas) in the adjacent well. In some cases, the formation may present loss zones (e.g., fractures), and the sweeping fluid may be “lost” to the formation via such zones and bypass unswept zones. In such cases, the formation may be treated with an RPM to seal such fractured zones and prevent the sweeping fluid from being lost to the formation.
However, in some cases, whether it is a water production problem or a lost fluid problem, the size of the fractures (e.g., vugular zones) may be too large for the RPM to be effective, i.e., for the RPM to seal the fractured zones and prevent either the water production or the loss of a fluid (e.g., a sweeping fluid) to the formation. Thus, an ongoing need exists for more effective compositions and methods of sealing fractured zones in subterranean formations.